A Bothell woman in her thirties died from influenza complications on Jan. 4, the first flu death in Snohomish County this season. King County has also reported six flu deaths this season.

"Our flu surveillance has been telling us there’s definitely more activity," James Apa, communications manager for King County Public Health, said. Donn Moyer, media relations manager for the state Department of Health, said flu cases will likely continue to increase.

"Flu season in Washington typically peaks in January or February," Moyer said. "...Things are picking up pretty rapidly now."

Apa emphasized that the number of reported flu deaths is a low estimate, and therefore, the number of flu deaths isn’t a good indicator of how serious this flu season is. Flu isn’t required to be reported to the health department. Other deaths may not be reported as flu deaths because the person had flu as well as an underlying illness.

So what can you do to keep yourself and your loved ones healthy? Health authorities urge people to get vaccinated to prevent the flu and to seek treatment for serious flu symptoms.

Although flu season has already begun, it’s not too late to get a flu shot. Dr. Jeff Duchin, chief of the Communicable Disease section of King County Public Health, said the flu vaccine is "the best prevention measure" and helps both mild and serious cases of flu. The flu vaccine is recommended for everyone older than 6 months, but many people still don’t get vaccinated.

"Some people don’t think flu is a serious illness. That’s a common reason why people don’t get vaccinated," Duchin said. "The people who are most enthusiastic about getting vaccinated are the ones who’ve had influenza recently."

Other people don’t get flu vaccines because of cost, convenience, or concerns about the safety of vaccines — which Duchin said are "primarily unfounded." You can’t get sick with the flu from the flu vaccine.

Different strains of flu circulate every season, so it’s important to get a vaccine this season even if you’ve been vaccinated before. This season’s flu vaccine protects against H1N1, or "swine flu" — the most common flu strain this season and the same strain that led to 2009’s flu pandemic.

Flu often affects elderly people the worst, but H1N1 is more likely to affect younger and middle-aged adults. People with underlying health conditions such as diabetes, asthma, heart problems, lung problems or immunodeficiency are at a higher risk for severe influenza.

The Bothell woman who died of flu earlier this month had underlying health conditions, the Snohomish Health District reported. In King County, three of the people who died from flu were middle-aged with underlying health conditions, and three were elderly, Apa said.

Flu symptoms include body aches, fever, lung congestion, cough, sore throat, fatigue and headache. Mild cases of flu can be hard to tell apart from head colds, but if symptoms of a cold or flu are accompanied by a fever, you should go to the doctor, Moyer said.

Antiviral drugs can prevent the illness from progressing to more serious complications,

Duchin said, but they should be administered as soon as possible.

Where to get a flu shot:

• Visit flushot.healthmap.org to find pharmacies near you that offer flu shots.

• Snohomish County will host free flu shot clinics that are open to anyone next week.